The present disclosure relates to a poppet valve that can be used for aseptic product lines.
Poppet valves are used as seat valves, double seat valves or control valves for product guidance in the sphere of food production, beverage treatment and/or filling plants. Seat valves for hygienically demanding applications have valve stem seals, so as to seal the valve cavity during the valve stroke. In the case of aseptic applications, the areas through which the product flows have to be sealed hermetically against the surroundings and against drives and control units associated with these areas. For this purpose, the closing element projecting into the product space of the poppet valve can be sealed hermetically against the valve housing by bellows or a disk-shaped membrane.
A poppet valve comprising a disk-shaped membrane integrated in the closing element is known from EP 1 527 296 B1. The membrane is axially compressed at a fixing site, which is located on the side of the valve housing, in an axial direction between a stop formed on the valve housing and a sealing ring, and is fixed in this way.
DE 10 2005 016387 B3 additionally discloses a poppet valve comprising a disk-shaped membrane, which is fixed to the valve housing at an inner fixing site on the closing element and at an outer fixing site on the valve housing. The membrane is stabilized by support elements that interengage in the manner of a serrated lock washer, said support elements being fixed to the cover of the valve housing and to the stem of the closing element.
For sealing such membranes against the valve housing, elastomeric seals as well as a press fit without additional seals can be used. An aspect of elastomeric seals is that they are often not sufficiently resistant to products and/or cleaning media. Fixing the membranes by means of a press fit entails the risk of an excessive load on the membrane. Particularly problematic is the fixing of the membrane at a metal stop in the valve housing under a defined preload of the membrane. Moreover, reliable as well as infiltration-free sealing of the product space should be maintained over the longest possible service life.
U.S. Pat. No. 4,666,166 indeed suggests a disk spring for fixing a membrane, which is curved similar to a bellows, on the valve housing. However, this is only practicable for comparatively thick membranes and without any preload.
Hence, there is a demand for a poppet valve which is improved in comparison with this conventional art.
The posed task is solved by a poppet valve described herein. This poppet valve is suitable for aseptic product lines. The poppet valve comprises a valve housing with line connections and a valve seat formed between these line connections in the valve housing, a closing element, which is axially displaceable in the valve housing and which cooperates with the valve seat, and a membrane extending around the closing element and from the latter up to a fixing site on the housing side.
According to the present disclosure, the poppet valve additionally comprises a spring-elastic and/or annular element used for fixing the membrane under preload on the housing side. The spring-elastic element is here subdivided towards the fixing site into partially circumferential segments. These segments have additionally formed thereon extensions, which press the membrane against the fixing site that may be cylindrical and/or sectionwise conical and which, in so doing, compress the membrane. In the course of this process, the membrane is elastically compressed and potentially also plastically deformed, so that the extensions will dig into the membrane.
The partially circumferential segments allow the membrane to be uniformly pressed against the fixing site, which is located on the housing side, and they allow to achieve a reliable hermetic sealing of the valve cavity at the fixing site.
The extensions are configured such that, in the mounted condition, they engage the membrane under compression of the latter, without tearing the membrane. This may have the effect that the membrane is, at least partially, elastically compressed and potentially plastically, i.e. permanently, deformed. By penetrating/digging into the membrane, the extensions allow a connection between the spring-elastic element and the membrane in the area of the sectionwise cylindrical and/or conical fixing site in the pulling direction, whereby the membrane will be prevented from being torn out of the fixing site. Pulling forces acting on the membrane and, consequently, on the extensions will press the partially circumferential segments still further against the housing-side sealing site and/or against a sealing edge, and increase the sealing effect in this way.
In addition, the extensions and the membrane in the area of the fixing site may also engage one another at areas which have been preshaped such that they are adapted to one another. This means that the membrane is preshaped for form-fit engagement, e.g. with recesses complementary to the extensions.
The valve housing has potentially two line connections for a fluid, which may e.g. be a product, a product component, a cleaning medium, a supply medium or the like. The valve seat is potentially arranged at the transition of the valve housing to one of the line connections.
Two poppet valves of the type in question may, however, also be combined in series so as to form a double seat valve. Each poppet valve of the double seat valve will then have a membrane, a spring-elastic element and a fixing site, which cooperate according to at least one of the embodiments described.
The membrane is configured for hermetically sealing the valve cavity, which is enclosed by the valve housing, the valve seat, the closing element and the membrane.
The closing element comprises a valve disk and a valve stem. The membrane is either connected to the closing element at a further fixing site or formed integrally with the closing element.
Fixing the membrane under a preload means that the membrane is elastically stretched between the closing element and the housing-side fixing site in the closed condition of the poppet valve as well as in the open condition of the poppet valve.
The extensions are potentially formed integrally with the partially circumferential segments of the spring-elastic element. The extensions are e.g. finger-shaped and/or claw-shaped. The term “spring-elastic” means that a spring effect may be achieved by elastically bending individual supporting structures, but not by compressing them. Hence, the spring-elastic element acts as or similarly to a spring clip.
In one embodiment, the partially circumferential segments have a rounded and/or chamfered sealing profile in a contact area with the membrane. The sealing profile provides a sealing edge extending circumferentially around the spring-elastic element. This sealing edge is forced into the membrane and presses the latter along the entire circumference of the fixing site against the valve housing in a hermetically sealing manner. The individual partially circumferential segments allow the shape of the spring-elastic element to be adapted to the fixing site, which adaptation is due to manufacturing tolerances and/or the mounting positions of the spring-elastic element and of the membrane existing in practice at the fixing site.
In one embodiment, the extensions project at an oblique angle outwards from the partially circumferential segments such that they are directed away from the valve seat. This allows a permanently steady axial position of the membrane in spite of the preload and prevents the membrane from being torn out of the fixing site in spite of the dynamic load occurring when the poppet valve is in operation.
In one embodiment, a distance between the partially circumferential segments is, in a contact area with the membrane, smaller than the thickness which the fixed membrane has there. In this way, a reliable hermetic seal can be accomplished also in the circumferential subareas located between the segments. In particular, the product or the like can reliably be prevented from entering the area behind the membrane along the entire circumference of the membrane.
In one embodiment, the membrane has a substantially cylindrical outer edge portion, which is clamped in position between the extensions and the fixing site. The edge portion is potentially adapted to the original, i.e. still non-deformed contour of the spring-elastic element and configured elastically such that, when it is being installed in the valve housing, it will adapt itself to the cylindrical fixing site and create a preload in the extensions in this way.
In one embodiment, the poppet valve further comprises an anchoring ring for supporting and for form-fit anchoring of the spring-elastic element on the valve housing, and a support ring for supporting the membrane under preload, such as in the open condition of the valve. The anchoring ring and the support ring are interconnected in a form-fit manner or by a material bond, so as to fix the spring-elastic element between the fixing ring and the support ring. The connection can be established by a thread, by crimping, by a bayonet lock or by welding. This allows simple mounting of the membrane and of the spring-elastic element. The support ring is configured for supporting a radially outer portion of the membrane.
In one embodiment, the poppet valve further comprises a metal stop formed on the valve housing and used for axially anchoring the anchoring ring. The metal stop is formed in the area of a flange connection between the valve housing and the control casing. The anchoring ring can be installed in the separated condition of the flange connection and, when the flange connection has been closed, it is axially and possibly also radially fixed in the valve housing.
In one embodiment, the support ring has a support profile for the membrane, said support profile having a substantially concave curvature towards the valve seat. The membrane will then potentially rest on a support surface provided with the support profile along the entire circumference thereof. The concave curvature allows a uniform preload at different axial positions of the closing element.
In one embodiment, the poppet valve further comprises a support body secured to the closing element and used for supporting the membrane, such as in the closed condition of the valve. The support body is configured for supporting a radially inward portion of the membrane. The support body will then potentially have a support profile having a concave curvature, said support profile being formed on the support body towards the valve seat. This allows a uniform preload of the membrane in the closed or almost closed condition of the valve.
In one embodiment, the closing element comprises a valve disk and a valve stem, the membrane being fixed in position between the valve stem and the support body. The valve stem and/or the valve disk may be formed integrally or as multi-part components. The valve disk, the valve stem and the support body may be connected to one another e.g. by means of a central bolt.
In one embodiment, the spring-elastic element consists of a metal or a metal-containing composite material. In this way, the spring-elastic element will permanently press the membrane against the fixing site under a sufficiently high preload, even if the internal stress of the membrane should decrease. In addition, metals or metal-containing composite materials are particularly resistant to thermal loads and loads occurring during the mounting process.
In one embodiment, the spring-elastic element consists of a plastic material, in particular PEEK, or of a composite material containing plastic. This allows the spring-elastic element to be produced at a comparatively reasonable price by injection molding or the like.
In one embodiment, the plastic material or the composite material containing plastic will then be temperature resistant up to at least 150° C. and, in particular, up to at least 200° C. The poppet valve can thus be used for hygienically demanding treatments of products, e.g. in beverage treatment and/or filling plants, and in particular in/on aseptic product lines.
In one embodiment, the poppet valve is pneumatically driven and configured as an aseptic seat valve, aseptic double seat valve or aseptic control valve. The likewise thermally and mechanically stable fixing of the hermetically sealing membrane can be used in such valves in a particularly advantageous manner.
The posed task is also solved by a beverage treatment and/or filling plant utilizing the poppet valves of the embodiments. This plant comprises at least one poppet valve according to at least one of the above described embodiments.